1. Field of the Invention
The invention relates to cosmetic preparations with a pearlescent effect and good skin compatibility, and to the use thereof.
2. Discussion of Background Information
Customary cosmetic application forms and preparations are often emulsions. This term is generally understood as meaning a heterogeneous system of two liquids which are immiscible or miscible only to a limited extent with one another and are usually referred to as phases. One is in the form of droplets (disperse or internal phase), whilst the other liquid forms a continuous (coherent or internal) phase. Less common application forms are multiple emulsions, i.e. those which, in the droplets of the dispersed (or discontinuous) phase, comprise for their part droplets of a further dispersed phase, e.g. W/O/W emulsions and O/W/O emulsions.
More recent findings have recently led to a better understanding of cosmetic emulsions which are of relevance in practice. Here, it is assumed that the emulsifier mixtures used in excess form lamellar liquid-crystalline phases or crystalline gel phases. In the gel network theory, stability and physicochemical properties of such emulsions are attributed to the formation of viscoelastic gel networks. In order to be able to ensure the metastability of emulsions, interface-active substances, i.e. emulsifiers, are usually necessary.
Emulsions from the prior art have a pearlescent effect, as is described, for example, in WO 0110403, WO 9010429, DE 19921186 or DE 19944545. These cosmetic preparations comprise mono- and di-fatty acid esters of glycerol or glycol, such as, for example glycerol stearates, laurates or myristates, in order to ensure pearlescence of the preparation. These fatty acid esters form lamellar structures with lyotropic, liquid-crystalline properties arranged in O/W emulsions. This leads to an optical property of the emulsions comprising them which is referred to as pearlescence.
Preparations with pearlescence optics without the addition of these fatty acid esters are not accessible or accessible only with difficulty.
Cosmetic preparations and emulsions with pearlescence optics based on the emulsifier “stearic acid/palmitic acid” have been known for a long time. It was hitherto not possible to formulate pearlescent emulsions which have the neutralizing agent NaOH and fractions of fatty acids below 12% by weight.
In view of this, the pearlescent emulsions known from the prior art and available commercially exhibit very poor skin compatibility.
An optical pearlescent effect is achieved in cosmetic preparations according to the prior art exclusively by neutralization with triethanolamine or potassium hydroxide solution. With sodium hydroxide solution, no systems with mother of pearl-like optics could hitherto be prepared, as detailed, for example, in Modern Cosmeticology, Volume one, 1996, Ralph G. Harry, F. R. I. C, 1962, pp. 115-119. It is likewise clear in this that lipids and waxes inhibit the pearlescence in emulsions. Pearlescent emulsions are described which comprise very small, up to a maximum of 3% by weight, fractions of lipids and/or lipophilic consistency-imparting agents.
In addition, it is known that the sole use of sodium hydroxide solution in these systems does not ensure adequate storage stability of the cosmetic preparation, as explained, for example, in The American Perfumer, April 1945, “Manufacturing Vanishing Cream”, J. S. Shukla. This also discloses that pearlescent emulsions can be achieved exclusively by means of high use concentrations of fatty acids. Thus, for example, 16-25% by weight of fatty acids, where 13.3% by weight should be hydrolysed, are used. However, it is also known, for example from Kosmetologie, 3rd edition, 1976, Dr. J. Jellinek (pp. 235-239), that precisely this high soap content of 13.3% by weight leads to poor skin compatibilities.
Cosmetic preparations with pearlescent effects have visible effects in the product, although these are no longer visible on the skin or are different from the subsequent appearance on the skin.
It is therefore customary to add pigments or dyes to the preparations in order to enhance the effect on the skin. A disadvantage of preparations to date with pigment additives without pearlescent effects is that the preparations have no shimmer effect within the product. The disadvantage associated with this is that although preparations to which pigments have been added have a shimmer effect on the skin, they do not have a shimmer effect within the product. The user can in no way discern the optical effect to be achieved on the skin by reference to the product.
An object of the present invention is to provide a cosmetic preparation which has an optically pleasing effect, in particular a pearlescent effect, adequate storage stability and, in particular, good skin compatibility. In particular, the object of the present invention is to provide a preparation with pearlescent effects which offers this effect both on the skin and also within the product.
Moreover, the object of the present invention is to provide a cosmetic preparation which enriches the prior art.